The present invention relates generally to diode array spectrophotometers, and more particularly, to a direct mount fiber optic array coupler for use with a diode array spectrophotometer.
Diode array spectrophotometer designs typically employ a sealed spectrophotometer unit comprising a polychromator that includes an entrance slit, a holographic grating, and a diode array detector. Diode array spectrophotometers are considered to have "reversed optics", in that all wavelengths of light excite the sample, and are usually considered to be nonconventional relative to a forward optics spectrophotometer wherein filtered monochromatic light is employed.
Polychromatic light from a light source is passed through a sample under investigation and is coupled to the spectrophotometer unit by way of a focusing lens arrangement that focuses light onto the entrance slit of the spectrograph. The standard configuration of a Hewlett-Packard spectrophotometer model HP 8452A includes a lens to focus light onto the entrance slit. This arrangement works very well for non-remote application. When using fiber optics for remote sampling, the goal is to minimize the light loss by optimizing the fiber-spectrograph interface. Conventionally this is done by butt-coupling the fiber onto the slit and is characterized by a significant reduction in light throughput.
With conventional fiber optic designs, light from the source is inefficiently coupled into the spectrophotometer unit. Light loss occurs at the interface between the fiber optic waveguide bundle and the entrance slit. Light losses of as much as 90% can occur in such conventional systems.
Accordingly, it is an objective of the present invention to provide for an improved fiber optic coupling for use with a diode array spectrophotometer. It is a further objective of the present invention to provide for a fiber optic coupling that limits light loss at the diode array spectrophotometer entrance.